1. Field of the Invention
The present invention relates to a stepping motor control circuit which drives various objects, an electronic camera, and a stepping motor control method.
2. Description of the Related Art
A conventional stepping motor control circuit controls a stepping motor which drives the zoom lens of an electronic camera. The stepping motor control circuit comprises a system controller and zoom lens driving circuit. When the zoom switch is turned on, the system controller operates on the basis of a program, enters the zoom mode, and controls the zoom lens driving circuit to start pulse driving of the stepping motor. Subsequently, the system controller adds or subtracts an output driving pulse value P, stores the resultant pulse value P, and calculates zoom position data corresponding to the stored pulse value P. The system controller controls pulse driving of the stepping motor on the basis of the calculated zoom position data and zoom position data which is stored in the system controller in advance. The system controller compares the driving pulse value P with a pulse value corresponding to the original zoom position data which is stored in the system controller in advance. When these pulse values do not coincide with each other, the system controller corrects the zoom position data which is stored in the system controller in advance.
The stepping motor driving method includes a 1-1 phase driving method (excitation method) of sequentially exciting stators of four phases or the like phase by phase, a 1-2 phase driving method of alternately repeating one-phase driving (excitation) and two-phase driving, and a 2-2 phase driving method of driving stators for two phases. In practice, the one-phase driving method is rarely employed because of a small torque. The 1-2 phase driving method has an advantage of implementing smooth rotation, whereas the 2-2 phase driving method has an advantage of implementing stable rotation. To exploit these advantages in accordance with the driving form, there has been proposed a stepping motor driving method of selectively operating the stepping motor by the 1-2 phase driving method and 2-2 phase driving method.